This invention relates generally to dynamoelectric machines and more particularly to a quadrature winding retention apparatus for a dynamoelectric machine.
Dynamoelectric machines, in the form of electric motors, have numerous applications, such as for an air handler, washing machine and compressor motors. An important part of the utility of such motors is the ease of manufacturability. Manufacturers require inexpensive, yet reliable and efficient motors for appliances or other tightly packaged machines. Thus, manufacturers see a need for a motor that can be rapidly and economically manufactured without sacrificing package space, manufacturing cost efficiency, and operating cost efficiency.
Dynamoelectric machines also need to be commutated such that the controller alternates the direction of the electrical current inducing rotor rotation when the back electromotive force and motor current are at the proper phase relationship. This ensures that the machine does not waste electrical energy by switching the current direction too early or too late and working against the momentum of the motor. To commutate a dynamoelectric motor properly, accurate rotor position information is essential and readily available through various rotor position sensors. Without information from position sensors, electronically commutated dynamoelectric motors will not operate.
Quadrature winding technology offers a promising, low cost alternative to a Hall Effect sensor. Quadrature windings sense rotor position for commutation, but are more appealing than Hall Effect sensors because they provide more accurate information and can be added to a sealed motor system with a minimal number of wiring leads and connectors.
A quadrature winding comprises a single insulated conductor oriented in a channel in the center of the radially inner end of a stator tooth, wound to an adjacent tooth end, and oriented again in a center channel of the adjacent stator tooth end. Channels are added to the stator tooth ends to keep the rotor from striking the conductor and to minimize the gap size caused by sensing devices between the stator and rotor. In the past, production motor designs did not incorporate quadrature winding technology because of poor manufacturability and high labor costs. Operators experience difficulty hand winding the quadrature because the wire required constant tension while wound to ensure that the previous windings did not loosen. Hand winding was unattractive for production motors because automated winding techniques yield faster, less expensive, and more accurate results.